Andy Murray of Britain returns a shot to Steve Johnson of the US during their men's singles match at the Shanghai Masters tennis tournament in Shanghai, China, October 14, 2015. [Photo/Agencies]

"I felt good," said Murray, who's competing for the first time since leading Britain into the Davis Cup final with victory over Australia in Glasgow three weeks ago.

"I thought I moved well from the beginning, struck the ball cleanly. From my side, I was happy with the way that I played and also the way my body felt. I thought I moved around the court very well. That's obviously an important part of my game. That was key."

He will in the third round take on another American and No. 13 seed John Isner, who won 6-3, 7-6 (5) over Belgian David Goffin and powered a whopping 21 aces on his way to the victory.

Elsewhere, fourth seed Stan Wawrinka maintained his winning run, defeating Viktor Troicki of Serbia 7-6 (3), 6-3 while sixth seed Kei Nishikori of Japan came back from one set down to defeat Nick Kyrgios of Australia 1-6, 6-4, 6-4 to also reach third round.

Eighth seed Rafael Nadal of Spain overcame some dicey moments to edge past big-serving Croat Ivo Karlovic 7-5, 6-7(4), 7-6(4).

Major upset came from seventh seed David Ferrer of Spain, who lost to Australian rising star Bernard Tomic 6-4, 6-2.

There were also second round victories for fifth seed Tomas Berdych from the Czech Republic and Canadian ninth seed Milos Raonic.